1. Field of the Invention
The present invention relates, in general, to methods and devices for switched data communication, and, more particularly, to methods and devices for measuring traffic analysis within a fibre channel switch.
2. Relevant Background
Fibre Channel is a high performance serial interconnect standard designed for bi-directional, point-to-point communications between servers, storage systems, workstations, switches, and hubs. It offers a variety of benefits over other link-level protocols, including efficiency and high performance, scalability, simplicity, ease of use and installation, and support for popular high level protocols.
Fibre channel employs a topology known as a "fabric" to establish connections (paths) between ports. A fabric is a network of one or more switches for interconnecting a plurality of devices without restriction as to the manner in which the switch can be arranged. A fabric can include a mixture of point-to-point and arbitrated loop topologies.
In fibre channel a path is established between two nodes where the path's primary task is to transport data from one point to another at high speed with low latency, performing only simple error detection in hardware. The fibre channel switch provides flexible circuit/packet switched topology by establishing multiple simultaneous point-to-point connections. Because these connections are managed by the switches or "fabric elements" rather than the connected end devices or "nodes", fabric traffic management is greatly simplified from the perspective of the device.
Fibre channel fabric devices include a node port or "N_Port" that manages the fabric connections. The N_port establishes a connection to a fabric element (e.g., a switch) having a fabric port or F_port. Devices attached to the fabric require only enough intelligence to manage the connection between the N_Port and the F_Port. Fabric elements include the intelligence to handle routing, error detection and recovery, and similar management functions.
A switch is a multi-port device where each port manages a simple point-to-point connection between itself and its attached system. Each port can be attached to a server, peripheral, I/O subsystem, bridge, hub, router, or even another switch. A switch receives a connection request from one port and automatically establishes a connection to another port. Multiple calls or data transfers happen concurrently through the multi-port fibre channel switch. A key advantage of switched technology is that it is "non-blocking" in that once a connection is established through the switch, the bandwidth provided by that connection is not shared. Hence, the physical connection resources such as copper wiring, fiber optic cabling and radio frequency bandwidth can be more efficiently managed by allowing multiple users to access the physical connection resources as needed.
Switched communication systems work most efficiently when the switch resources are allocated efficiently. In other words, in a multi-port switch, each of the ports desirably processes an equitable amount of data traffic. When one connection through the switch absorbs an unbalanced amount of traffic, traffic delays are caused even while the switch possesses unused resources (i.e., unused ports and connection resources). The end result of an unbalanced switch is unnecessary average latency in processing traffic caused by bottlenecked connections within the switch.
User's desire knowledge about the data traffic that flows through a switch in order to efficiently manage that data traffic and avoid bottlenecks. A switch is most efficiently used if the traffic load through that switch is reasonably balanced. When a particular switch port or ports are used heavily by a single host or destination those ports are not available to handle other traffic. Similarly, it is desirable to have knowledge about the type of data traffic flowing between a pair of ports. In a fibre channel system, for example, the data traffic may comprise any of a number of FC-4 specified frame types. Knowledge of the frame type can be used to configure and reconfigure the communication network for more efficient utilization of resources.
Prior approaches provide a means for counting received or transmitted frames on a single port basis. This allowed a user to monitor traffic at a single switch node, however, does not provide an mechanism to reliably correlate the traffic between a source port and a destination port within the switch. In other words, the prior approaches enable one to monitor the traffic from a node port to a switch port, but not from one switch port to another switch port. The prior approach enables one to determine if a particular path or port is experiencing an unusually high load, but does not provide sufficient information to determine what host(s) is/are driving the port. If multiple hosts are driving the port, prior approaches are unable to identify the proportionate share of the load of the port for which each of the driving hosts is responsible. Moreover, because prior approaches are not protocol specific, it is difficult or impossible to tell what type of traffic is consuming the bandwidth of a particular host port.
A need exists for a method and device for measuring. protocol traffic that provides information about traffic within a switch from a source port to a destination port. A need also exists for an analysis tool that measures traffic on a protocol specific basis.